1. Field of the Invention
This invention relates to a development-agent container for containing development agents in a development apparatus in an electrophotographic image forming apparatus, a process cartridge, and an image forming apparatus.
2. Related Background Art
In an image forming apparatus of an electrophotographic system, in other words, in an apparatus for obtaining images by developing with development agents, electrostatic latent images on an image carrier, such as a photosensitive drum or the like, it is required to supply development agents as expendables. As a method for supplying development agents, there are the following methods.
First of all, a development-agent receiving container is installed in an image forming apparatus body, such as a photocopier or the like, and a development-agent supplying container, filled with development agents in advance for supplying development agents, is prepared as another expendable, independent from the image forming apparatus, and when the development-agent receiving container comes to have the smaller remaining amount of the development agents, the development agents in the development-agent supplying container are supplied, as a supplying method, in the whole amount at once to the development-agent receiving container.
As another method, there is a method using a stationary container, in which, though a development-agent supplying container is prepared in the same way as the above method, after a development-agent supplying container is attached to the image forming apparatus body without supplying the agents in the whole amount, the development-agent supplying container is left over as it is in the image forming apparatus body, and the development agents are gradually delivered toward a development apparatus by operating a development-agent stirring apparatus until the development agents are used up.
In addition, there is a process cartridge method in which a photosensitive drum, a cleaning apparatus, and a development apparatus filled in advance with development agents, are formed unitedly and in which those elements are detachably attached to the image forming apparatus body. In this method, development agents are delivered gradually to a development sleeve and a photosensitive drum from a development-agent containing section formed in the cartridge by operating a development-agent stirring apparatus until the incorporated development agents are used up where the cartridge is attached once in the image forming apparatus body.
However, in all the methods, it is required to detect the remaining amount of the development agents in the development-agent container, and the remaining amount is detected by a light transmission method, an antenna method, and like.
FIG. 5 is an illustration of a development apparatus performing detection of the development-agent remaining amount through a light transmission method; FIG. 6 is a diagram illustrating the relation between a toner-remaining amount and a light-transmission time. A development apparatus 100 shown in FIG. 5 is structured of a development unit 107 in which a development sleeve 105, a development agent supplying roller 106, and so on are installed, and a development-agent container 104 welded thereto for containing the development agents. Light-transmission windows 101, 102 for detecting the development-agent remaining amount are attached to the development-agent container 104. A stirring member 103 is rotatively attached to the interior of the development-agent container 104 to stir the toners T serving as development agents, and is driven in an arrow AA direction by a drive means, not shown. The stirring member 103 is constituted of a stirring stay 103a connected to the drive means and a flexible stirring sheet 103b for removing the toners clinging to the light-transmission windows 101, 102.
In the image forming apparatus body, a light-emitting portion 108 and a light-receiving portion 109 are arranged, and the detection light L is emitted from the light emitting portion 108, transmitted through the light transmission windows 101, 102, and received at the light-receiving portion 109 to detect the remaining amount of the development agents T in the development agent container 104. More specifically, the detection light L is emitted for a period while the stirring member 103 rotates for one turn, and time t that light transmits in the development-agent container 104 is detected during this period. When this amount exceeds a prescribed threshold t1, it is judged as toners remain in a small amount, and the apparatus notifies it to the users.
With the development apparatus thus structured, though the stirring sheet 103b is structured to wipe the surfaces of the light-transmission windows 101, 102 by a rotation of the stirring member 103 during the detection operation, the stirring sheet 103b is at a position shielding the detection light L from starting wiping the light-transmission window 101 to ending wiping the light-transmission window 102. Although a flexible sheet, such as PET, is frequently used for a material of the stirring sheet, such a conventional sheet is generally transparent or semitransparent, which has low light-shielding property.
Where the toner-remaining amount is relatively large in the development-agent container 104, toners clings to the surface of the stirring sheet 103b in a large amount, and when the stirring sheet 103b is on a beam axis of the detection light L, the stirring sheet 103b also shields the detection light L. However, if the toner-remaining amount become small, situations that the sheet can shield the light and cannot shield the light may occur, depending on the toner amount clinging to the stirring sheet 103b. In addition to the toner-clinging degree on the stirring sheet, situations that the sheet can shield the light and cannot shield the light may occur depending on differences in the light emitting of the detection light and sensitivity of the light receiving sensor.
FIG. 6 is a graph showing a relation between a toner amount in the development-agent container 104 and the transmission time t of the detection light. If the toner amount M is reduced, the transmission time t increases, and when the time t exceeds the threshold t1, the apparatus issues a warning of "empty of toner amount." However, as described above, with the conventional structure, where the toner amount is small, the stirring sheet 103b may shield light in some case but may not shield light in other cases, and when the light is shielded, it becomes a curve as shown with numeral S1, whereas when the light is not shielded, it becomes a curve as shown with numeral S2. The toner-remaining amount M where the transmission time t exceeds the threshold t1 is M1 when the light is shielded and M2 when the light is not shielded, and generates large differences.